AKT. 27 ASYMMETEY IN SKULLS OF MAMMALS HOWELL 5 



Inquiring more fully into the pathological situations present it is 

 found that — 



(a) The right mastoid is unusual only in being shortened laterally 

 and in having a marked process inferiorly. The lateral shortening 

 of the whole right side of the occipital is probably because of injury 

 to, and subsequent abnormal development of, the muscles originating 

 upon the infero-lateral part of its surface. 



(b) The deformity of the petrous portion of the temporal is not 

 marked, aside from its misplacement. Its chief point of interest lies 

 in the fact that there is almost complete closure of the jugular fora- 

 men and obliteration of its fossa, probably through the healing of a 

 small, diseased portion of both the petrous and occipital margins of 

 the foramen. The occipital was, perhaps, chiefly instrumental, for 

 its border has extended farther forward than normal, and the pet- 

 rous is correspondingly displaced. It is, of course, impossible that 

 the jugular vein was suddenly severed, else the animal had died at 

 once. Rather was its gradual atrophy brought about, enabling 

 other veins to care for the venous blood that is normally carried by 

 the right jugular. The functional alteration has not, however, re- 

 sulted in any increase in the size of the left jugular foramen, for the 

 latter is, in fact, smaller than seems to be usual in this genus. 



(c) The condition of the right auditory moatus indicates much 

 damage to the inner ear, very possibly causisig complete deafness 

 upon that side, induced by severe suppuration of the parts. The 

 passage is greatly enlarged, both superiorly and inferiorly, being 

 about 13 ram. in diameter, as against 7 for this measurement of the 

 left passage. The lateral length of the inferior border of the meatus, 

 measured from the carotid foramen, is about 18 mm. shorter upon 

 the right than the left side. This was evidently brought about by 

 suppuration and partial absorption of the bony lining of the meatus, 

 with subsequent healing and growth of new bony tissue only upon 

 its outer or inferior face. 



(d) The right glenoid fossa proper is not greatly altered, but the 

 eminentia articularis, anteriorly adjoining, is flattened and much 

 pitted. The same condition of pitting obtains upon the squamous 

 eminence adjoining the process of the tensor palati. The conditions 

 to be observed in the glenoid region are naturally correlated with 

 the following: 



(e) The right articular surface of the mandibular condyle is flat- 

 tened, broadened in an antero-posterior direction, and much pitted 

 and roughened, and the neck, as measured from the base of the 

 coronoid process, shortened by about 7 mm. It is very likely that 

 the functions of the abnormal side of the jaw were even more se- 

 verely interfered with than can now be told from an examination of 

 the skull, through destruction of part of the condyloid ligaments. 



